Annual report pursuant to Section 13 and 15(d)

Postretirement Health Care and Life Insurance Benefits (Weighted Average Assumptions Used To Determine Projected Benefit Obligations For Postretirement Obligations) (Details)

v3.7.0.1
Postretirement Health Care and Life Insurance Benefits (Weighted Average Assumptions Used To Determine Projected Benefit Obligations For Postretirement Obligations) (Details)
Jan. 28, 2017
Jan. 30, 2016
Other Postretirement Benefit Plan [Member]    
Discount rate 3.99% 4.15%